1. Field of the Invention
The present invention relates to an engine control system, a vehicle having the same, a method for calculating the combustion center of gravity of an engine, and a method for controlling an engine.
2. Description of the Related Art
A well-known method for optimizing the ignition timing of spark ignition internal combustion engines is a method of determining ignition timing on the basis of negative ion current in the cylinder (e.g., JP-A-6-33855). In the method disclosed in Patent Document 1, negative ion current flowing in the cylinder directly after ignition is measured, and the time from the ignition at which the value of the negative ion current becomes the maximum is determined. Then the time difference between the determined time and minimum spark advance for best torque (MBT) is calculated, and the calculated time difference is added to or subtracted from the preceding ignition timing to thereby determine the present ignition timing.